Heater with safety screen air inlet



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R. M. LILLY ETAL HEATER WITH SAFETY SCREEN AIR INLET Filed May 7, 1948 Nov. 21, 1950 o nnnnnnn cacao IN VEN TOR.

mm mm a RUSSELL M. LILLY BRUNO R. SCHABARUM 9 g 3 mm mm 8 k ATTORNEY Patented Nov. 21, 1950 UNITED STATES FATENT QFFiQE;

Russell M. Lilly, Wink, and Bruno n. Schabarum, Midland, Tex.

Application May 7, 1948, Serial No; 25,738

4 Claims. (Cl. 126-85) This invention relates to heaters and parsurroundings where explosive or inflammable atmospheres may be encountered and where the use of open flame heaters would be hazardous.-

The heater in accordance with this invention is designed particularly for safe use around oil drilling rigs and the like, where explosive or inflammatory atmospheres are frequently present. Such rigs are normally equipped with a small house or shelter, commonly referred to as a dog-house, located on or immediately adjacent to the derrick floor for the use of the Workman to change: clothes, rest or seek protectionfrom cold and inclement weather.

Because of the fire hazard, oil companies normally prohibit the use of open flame heaters in such dog-houses or anywhere in the immediate vicinity of the rig. Consequently, conventional practice is to set up a boiler unit at some distance from the rig and run steam lines to the dog-house, where steam radiators of conventional type are installed for furnishing the required heat. Such installations are quite expensive both in initial cost and in cost oi operation. Also they are relatively expensive to tear down, move and re-assemble when the drilling rig ismoved from one location to another.

A- primary object of the present invention is to provide a heater in which the flame is fully enclosed and fully guarded against the hazard of fire or explosion whenused in the presence of explosive or inflammable atmospheres.

An important object is the provision of a fully protected heater which is highly efiicient in operation, and is of compact unitary design which is adapted for relatively easy installation and portability.

A further object is the provision of a heater employing gaseous fuel. and which obtains its entire air supply for combustion through a single flame arrestor guarded inlet.

A- more specific object is the provision of a heater in which both. the pilot flame and. the principal burner flame are fullyenclosed and receive their entire combustion air supply through the same flame-guarded inlet.

Still another object. isthe provision oi a heater having the several novel features and advantages set forth. in the following description and illustrated in. the accompanying drawings illustrative of. one novel and useful embodiment in accordance with this invention.

In the drawings:

Fi 1 i a l n i udinal sectional elevation of .into a collar l'l surrounding opening it.

a heater in accordance with one embodiment of this invention; and

Fig. 2 is an enlarged view of the main burner assembly of the beaten Referring to the drawings, the heater, i accordance with the illustrative embodiment, comprises a combustion chamber H)- of elongated tubular form and horizontally disposed. One end of chamber it is closed by an endwall II, in the center of which is connected a short threaded nipple I2 closed by a screw cap l3 having therein a window [4 of glass or other suitable transparent material to provide a sight opening to the interior of the chamben An upwardly extending exhaust stack or chimney l5, provided with the usual adjustable damper I5a, com municates with the interior of chamber It) through an opening it at a point adjacent end wall I I. Chimney I5 is conveniently constructed of a piece of ordinary pipe and is threaded at its lower end so that it may be tightly screwed The upper end of chimney i5 is closed by means of a cover plate and the upper end portion of the wall of chimney I5 is provided with a plurality of perforations 36. Wire gauze or screen 31 is wrapped around the exterior of the perforated portion of' chimney l5 generally to a thickness of about three layers of screen and forms a flame arrestor for the chimney exit;v

Screen 31 is held tightly in place over perforations 36 by means of suitable clamping bands 38-38 which may be applied in any conventional or well-known manner. A tubular guard 39 concentrically surrounds the screened portion of chimney l5, and is rigidly connected to. the chimney below screen 31 by means'of an annular end wall 40 through which a plurality of perforations 4! are provided. The upper end of guard 39 is open and a conical hood 42 is mounted-on cover plate 35 in such manner that the walls of the hood extend over the open end of guard 39 and are vertically spaced therefrom. The opposite or inlet end of combustion chamber I 3 is also closed by an end wall is at the upper edge of which a sloping surface is is provided; to which is connected a threaded nipple 2-9 closed by a screw cap 2! in the center of which is mounted a window 22 of glass or other suitable transparent material to provide a. sight opening through which the inlet portion. of the chamber may be viewed. A burner opening 23 is provided:

in end wall is adjacent its lower edge and enclosed by a threaded collar 2t rigidly fastened orwelded tothe exterior ofend wall It. Screwed into collar 24 is tubular casing 25 which is adapted to enclose the burner and fuel supply elements of the heater. Casing 25 may also be constructed from a suitable length of standard pipe. The outer end of casing 25 is threaded and has screwed thereon a T-fitting 26, which is connected thereto through one end of the top of the T. The other end of the top of the T is closed by means of a tubular bushing 21. Screwed into the center leg of the T-fitting 28 is a short length of pipe 28 which is closed at its lower end by means of a cover plate 29 and provided with a plurality of perforations 36 throughout a substantial portion of its length. Wire gauze or screen 3| of suitable mesh size is wrapped around the exterior of the perforated portion of pipe 28. A sufficient number of courses of screen are thus wrapped around pipe 28 to provide a layer of screen about one-half inch thick. The screen is held in place by suitable clamping bands 32-32 which may be applied in any conventional and well known manner to hold the screen firmly in place over the perforations in pipe 28. A tubular shroud or guard 33 concentrically surrounds screen 3| and is closed at its upper end by an annular wall 34 which is welded or otherwise tightly fastened to pipe 28 above the upper end of screen 3|. The lower end of guard 33 is open to the atmosphere. Pipe 28 constitutes the combustion air inlet for the heater and screen 3| constitutes the flame arrestor for this air inlet.

A mixing tube 43, of the conventional Venturi shape is mounted axially of casing 25 with its discharge end extending through opening 23 into the interior of combustion chamber ID. A radial spacing and support block 44 is mounted on the exterior of mixing tube 43 to center it in casing 25 and cooperates with a block 45, suitably disposed on the inner wall of casing 25, to fix the longitudinal position of the mixing tube in the casing. A screw 46 extends through the wall of casing 25 at the rear of support block 44 to lock the mixing tube in the desired position against block 45.

A fuel supply pipe 41 extends axially through the bore of bushing 21 and thence through and across the top of the T-fitting 26 into casing 25 and is provided with a constricted burner tip 48 which extends into the inlet end of mixing tube 43. The outer end of fuel pipe 41 is supported on a c-bracket 49 which extends rearwardly from the outer end of bushing 21. Fuel pipe 41 is firmly clamped to bracket 49 by means of a set screw 50. The outer end of fuel pipe 41 is fitted with a connection to which is connected a flexible hose 52 through which fuel is supplied to pipe 41.

A tubular sleeve 53, concentric with fuel pipe 41 and slidable thereon, extends through th bore of bushing 21. Rigidly mounted on the inner end of sleeve 53 and transversely thereof is an annular disk 54 which is adapted to form an air regulating valve for the supply of combustion air entering mixing tube 43. The outer end of sleeve 53, which extends outwardly beyond bushing 21, is provided with a stuffing box 55 adapted to form an air tight seal between sleeve 53 and fuel pipe 21. An annular packing nut 56 slidably surrounds fuel pipe 41 and is adapted to compress the packing conventionally provided in stuifing box 55. The outer end of the bore of bushing 21 is enlarged somewhat in diameter and internally threaded to receive a conventional split ping bushing 51 which is slidably arranged on sleeve 53 to be threadedly received in the bore of bushing 21 to tightly clamp sleeve 53 in the bushing. It will be understood that when clamping nut 51 is loosened, sleeve 53 may be moved axially to adjust the position of disk 54 relative to the inlet end of mixing tube 43 in order to regulate the air supply to the mixing tube. When the desired adjustment has been made, tightening of clamping nut 51 will serve to fix the air regulating disk in the desired adjusted position.

A pilot burner tip 58 extends through the wall of combustion chamber 8 at a point spaced somewhat inwardly of the discharge end of mixing tube 43. A pipe nipple 59 connects pilot tip 58 to one end of a T-fitting 66, into the other end of which is connected a fuel supply pipe 6| having a control valve 62 mounted therein. The middle branch of T-fitting 66 is connected by means of a pipe 63 to the end of a second T-fitting 64 in the opposite end of which is mounted a conventional form of adjustable choke or valve 65 which is adapted to control the opening through the T. A pipe 66 is connected to the middle branch of T-fitting 64 and communicates through an opening 61 with the interior of casing 25 at an intermediate point thereof which may be opposite the throat of the Venturi mixing tube 43. A conventional union 68 is installed in pipe 63 for convenience in making up the fittings and connections.

Fuel supply pipe 6| is connected into one end of a T-fitting 68 into the other end of which flexible hose 52 is connected. A globe valve 10 is interposed between flexible hose 52 and its connection to T-fitting 69. A pipe 1| connects the middle branch of T-fltting 69 to a pressure regulating valve 12, controlled in the usual manner by a conventional pressure regulator 13. A fuel supply main 14 connects into the inlet end of regulating valve 12.

As the heater will normally be installed inside a building, casing 25 will be extended through a suitable opening in one wall A so that air inlet pipe 28 will be exterior of building. Casing 25 will have a pair of matching flanges 15 and 16 mounted thereon to clamp the edges of the wall opening tightly between them by means of bolts 11. Flange 15 will usually be welded or otherwise rigidly attached to casing 25 so that when the flanges are bolted up the casing will be firmly anchored to the wall and supported thereby. The opposite end of the heater structure will generally be provided with one or more longitudinally spaced legs 18-18 extending from the bottom of combustion chamber I 0 to the floor B of the building. Chimney |5 will usually extend through the roof C of the building.

The above-described heater which is designed to burn gaseous or vaporous fuel such as natural gas, butane, bottled gas or the like, operates in the following manner: The gas supply will enter through main 14 where it will be reduced to the desired burner pressure by means of regulating valve 12 and regulator 13 and fed into pipe 1| to T-fitting 69. Globe valve 1|! will be adjusted to regulate the quantity of gas going to the main burner assembly, While control valve 62 will be adjusted to regulate the quantity of gas going to the pilot burner tip 58. Under the natural draft induced through chimney l5, combustion air will be drawn from the atmosphere upwardly through the open end of guard 33 through inlet pipe 28, casing I5 and mixing tube 23 into combustion chamber I 0. The entering air will,

9; course. pass through flame arrestor screen 3| and perforations 3D in. enteringv inlet pipe 28. A portion of this air wi1l, -un'der the influence of the draft in the heater, be drawn through openingv 6i and pipe 66, under the control of valve 55 into and through pipe 63 and will mix with the gas flowing through pipe '9 to the pilot burner. Globe valve T5 will be closed at this stage of operation. One or: the other of the sight-opening caps i3'--2'l will be removed temporarily and a lighted taper or any other suitable ignition means will be: inserted through the sight open' ing into the combustion chamber in the vicinity of the pilot; burner to light the pilot flame, after which the cap will be replaced. When the pilotflame has been thus lighted and properly adjusted by suitable adjustment of the fuel and air supply valves 62 and 55, respectively, globe valve l-llwill be opened to admit fuel to the main burner assembly. This main fuel supply Will flow through ilex-ible'hose 52 and fuel pipe 47, thence through tip d8 into the inlet of mixing tube 43 where it will be mixed with the air flowing into the inlet of the mixing tube from the casing. The gas-air mixture will then flow through the mixing tube and as it discharges therefrom into combustion chamber If], the mixture will be ignited by the pilot flame and the heater placed in operation. By loosening clamping bushing 5i, sleeve 53 may be suitably manipulated to adjust the position of air regulating disk 54 relative to the inlet of the mixing tube so as to suitably regulate the quantity of air entering t e mixing tube to obtain the desired combustion mixture. Clamping bushing 5'3 will then be tightened to maintain this air regulation. The quantity of gas will, of course, be controlled by manipulation of globe valve 1!).

With the heater designed and operated, as above described, it will be seen the entire air supply both to the main and pilot burners will enter through a single inlet, namely inlet pipe 28, and must pass through flame arrestor 3| in entering the heater. All other possible openings for admission of air are closed tightly. The annular space between sleeve 53 and fuel supply pipe 41 is closed by means of stuffing box 55 and packing nut 56. The space between sleeve 53 and the bore of bushing 2'? is closed by means of clamping bushing 51, and the annular space between sleeve 53 and casing 25 is closed by means of bushing 21. The sight openings are tightly closed by means of the caps screwed thereon. The combustion gases will, of course, discharge from the heater through chimney l5, passing through perforations 36 and screen 3'! to the atmosphere. Since there is only a single air inlet and a single combustion gas outlet and both are thoroughly guarded by flame arrestor screens, the danger of a flash back through either of these openings is thus eliminated for all practical purposes and the heater is made safe for use in inflammable or explosive atmospheres.

With the tight construction described, excellent control of excess air becomes possible, thereby greatly increasing the efficiency of the heater.

It will be understood that the dimensions of the combustion chamber will be such as to provide any desired area of heating surface. For example, one useful size comprises a piece of ordinary 10% inch diameter pipe about nine feet long. As an additional factor of safety, the dimensions selected will normally be such that the surface temperature may be kept below the ignition point of any oil soaked rags or the like which may accidentally come in contact with the heater, while still providing sufficient radiating surface-toprovide the desired temperature in the room or space being heated.

In the form illustrated, it will be seen that all of the parts of the heater may be made of pieces of pipe ofsuitable sizes and thus provide a very compact and sturdy construction which, because of the various threaded connections employed, may be very readily torn down and assembled as required. Guards 38 and 39 and hood 42 serve to guard the flame arrestors from any oil or other liquid which often sprays about a drilling rig.

It will be understood the heater in accordance with this invention may effectively utilize liquid as well as gaseous fuels, the important factor in each case being the employment of a structure for fully enclosing the burner assembly in a manner to constrain the entrance of the entire combustion air supply through flame-guarded iniefiS'.

It will be understood that various changes; and alterations may be made in the form and arrangement of the details of the heater in accordance with the illustrative embodiment without departing from the scope of the appended claims but within the spirit of this invention. 7

What we claim and desire to secure by Letters Patent is:

l. A heater, comprisin a generally tubular combustion chamber having a burner opening in one end thereof and a chimney connected to the opposite end thereof, a closed tubular casing having one end in gas-tight connection with said burner opening, a removable closure in the outer end of said casing, a fuel pipe extending through said closure axially of said casing and having a burner tip on the inner end thereof, a mixing tube aligned with said burner tip and extending into said burner opening, a combustion air inlet pipe connected to said casing, flame-arresting means covering the intake end of said air inlet pipe, an air regulating disk valve mounted in said casing and axially adjustable relative to the inlet end of said mixing tube, a tubular operating stem for said valve concentrically mounted on said fuel pipe and extending through said closure, annular sealing means for sealing between said fuel pipe and said stern and between said stem and said closure, and means for supplying fuel to said fuel pipe.

2. A heater comprising, a generally tubular combustion chamber having a burner opening in one end thereof and a chimney connected to Q the opposite end thereof, a closed tubular casing having one end in gas-tight connection with said burner opening, a removable closure in the outer end of said casing, a fuel pipe extending through said closure axially of said casing and having a burner tip on the inner end thereof, a mixing tube aligned with said burner tipand extending into said burner opening, a combustion air inlet pipe connected to said casing, flame-arresting means covering the intake end of said air inlet pipe, an air-regulating disk valve mounted in said casing and axially adjustable relative to the inlet end of said mixing tube, a tubular operating stem for said valve concentrically mounted on said fuel pipe and extending through said closure, annular sealing means for sealing between said fuel pipe and said stem and between said stem and said closure, a pilot burner in said combustion chamber adjacent said burner opening, an air-supply conduit connected to said pilot burner and communicating with the in- 7 terior of said casing, and means for supplying fuel to said fuel pipe and to said pilot burner.

3. A heater, comprising, a combustion chamber having a burner opening and a chimney, a closed tubular casing having one end in gas-- tight connection with said burner opening, a single combustion air inlet in said casing through which the entire combustion air supply for said heater is admitted, flame-arresting means enclosing said inlet, a main burner assembly enclosed Within said casing, a pilot burner in said chamber adjacent said burner opening, an airsupply conduit connected to said pilot burner and communicating with the interior of said casing, control means in said conduit for regulating the supply of combustion air from said casing to said pilot burner, and means for supplying fuel to said main burner assembly and to said pilot burner.

4. A heater, comprising, a combustion chamber having a burner opening and a chimney, a closed tubular casing having one end in gastight connection with said burner opening, a single combustion air inlet in said casing through which the entire combustion air supply for said heater is admitted, flame-arresting means enclosing said inlet, a main burner assembly enclosed within said casing, air-regulating means for said main burner assembly enclosed Within said casing and adjustable from the exterior thereof, a pilot burner in said chamber adjacent said burner opening, an air-supply conduit connected to said pilot burner and communicating with the interior of said casing, control means in said conduit for regulating the supply of combustion air from said casing to said pilot burner, and means for supplying fuel to said main burner assembly and to said pilot burner.

RUSSELL M. LILLY. BRUNO R. SCI-IABARUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,237,858 Ballenger Aug. 21, 1917 2,178,703 Robbins Nov. '7, 1939 2,196,828 Hess Apr. 9, 1940 

